"Their chief failings in social competence are an inability to perceive themselves accurately and annoying others by their dominance and unsuitable jokes."
I think my favourite cover art from an actual TD release (not an Edgar Froese release) is... Rubycon. Quite simple but I love the colours and shape. I wish I had the LP, yet. For some stupid reasons, I kept with my tape for too many years before buying it a first time on CD.
And then I bought the definitive edition, which is so much better sound-wise but not artwork-wise, alas.. I do remember the inner photograph in the gatefold sleeve and it was absolutely magnificent.
Stratosfear is just behind, I think. Funny as musically, those are my two favourites too.